[okie01]

The same type of people who buy them now, I suspect.

But where does the money come from -- if we're saddled with a third world economy?

That won't make much of a market for heroin or coke. Even marijuana might be replaced by chewing coca leaf.

[Bigg Red]

I can’t pretend to know much about how such transactions work, but even supposedly poor people manage to buy drugs now. So I am sure the drug trade will continue just fine with people bartering with all sorts of goods and black market items.